The present invention relates to a magnetic recording and reproducing apparatus with mechanism for adjusting heights of guide poles (tape guides) provided at supply and take-up reel sides.
It is well known that track patterns formed on a magnetic tape according to rotational loci of magnetic rotary heads will be different from each other. This happens even though track patterns are formed by magnetic recording apparatuses of the same recording and reproduction standard due to difference in allowable mechanical tolerance.
This sometimes gives damage to data reproduced by a magnetic recording apparatus compatible with another magnetic recording apparatus by which the data has been recorded. The narrower the track patterns in high density recording, the more serious problem may happen.
For example, a W-VHS video tape recorder (VTR) has been proposed for recording and reproducing high vision-image data with simultaneous recording of parallel three track patterns each having 19 .mu.m-width. Two of the parallel three track patterns are used for video signal recording and reproduction with two rotary magnetic heads having azimuth angles in opposite directions. On the other hand, the remaining track pattern is used for audio signal recording and reproduction with an audio rotary magnetic head capable of after recording.
An allowable tolerance of curve on one track pattern in the W-VHS VTR is decided as about 7 .mu.m. This tolerance may cause about 14 .mu.m-deviation at maximum between track patterns of a magnetic tape recorded by a first W-VHS VTR and a rotary track of a rotary magnetic head of a second W-VHS VTR compatible with the first W-VHS VTR when after recording is done by the second W-VHS VTR.
If the 14 .mu.m-deviation happens, an audio rotary magnetic head for after recording of the second W-VHS VTR will be displaced from audio track patterns on the magnetic tape by 14 .mu.m to adjacent video track patterns each having 19 .mu.m-width. This results in recording of audio signal for after recording over a 14 .mu.m-width portion of the video track patterns each having 19 .mu.m-width.
Therefore, a reproduced video signal will be degraded because a 5 .mu.m-width portion only remains as the video signal.